In plasma display devices, conductor arrays disposed on glass plates are overcoated with a dielectric layer, and the glass plates sealed with the conductor arrays disposed orthogonal to each other, the conductor intersections defining display cells. By selectively applying appropriate signals to the conductor arrays, the display cells are discharged to provide a visible display, while forming a wall charge on the cell walls. The display is maintained by a lower amplitude sustain signal which combines with the wall charge potential formed at the selected intersections.
Fabrication techniques for plasma display devices are well known in the art, and are shown, for example, in U.S. Pat. No. 3,837,724, filed by Peter H. Haberland et al. Oct. 10, 1973. Another patent directed to gas panel fabrication is U.S. Pat. No. 3,804,609, filed by Thomas J. Murphy et al. on Dec. 30, 1971.
Such devices heretofore were of relatively small size and low resolution and possessed high operating margins, i.e., the difference between the maximum and minimum sustain voltages (V.sub.s max-V.sub.s min). The operating or reference point for the sustain voltage is some point between the maximum and minimum sustain voltage.
Due to the relatively large operating margin of such devices, sometimes designated the window, the adjustments for write, erase and sustain voltages of these panels could be preset at the manufacturing facility. End of life condition occurred when the sustain voltages either drifted or the voltage margin otherwise moved outside the specified tolerances. However, panels of larger size and higher resolution required a smaller discharge gap, i.e., the distance between the inner surfaces of the two plates, producing a decrease in voltage margin. With a low voltage margin, it becomes increasingly difficult to maintain the required uniformity for preselected adjustments since the operational characteristics of plasma display panels vary on a panel by panel basis.